Patent GB-714359-A (GB)
Title: Improvements in or relating to circuit arrangements for the connection of incoming and outgoing lines by means of selecting arrangements in telecommunication installations more particularly in automatic telephone installations
IPC: H04Q3/00
Filed: 1952-03-10
Abstract: 714,359. Automatic exchange systems. SIEMENS & HALSKE AKT.-GES. March 10, 1952 [March 10, 1951], No. 6210/52. Class 40 (4) A recurring series of pulses having a prescribed position in a cycle of such pulses is applied to a marking contact of a switch and to a voltage coincidence testing circuit in a stopping device for the switch, which is operative when the coincidence testing circuit receives coincident pulses directly and via a wiper of the switch which sweeps the marking bank. The different pulse positions may be allotted temporarily or permanently to control circuits to enable several control circuits to set several switches simultaneously using the same marking multiple. In the 1000-line exchange, Fig. 1, each group of 100 lines is allotted ten links such as AS1-VLW1 the former switches giving access to the subscribers' lines and the latter to a multiple over all such switches so that a call is set up over two of these links and the multiple. A calling line T111 starts in known manner a free switch AS1 which finds the calling line by. testing over the c-wiper. Simultaneously the associated switch VLW1 hunts for a free outlet in its multiple by testing over its c-wiper. The multiple also appears in the banks of the register-connecting switches such as SpW1 one of which is set to the seized outlet. Dialled digits are received by the equipment SE1, in the register Sp1, which sets the hundreds and tens digit switches H, Z, and one of the units digit switches E1 ... E10 depending on the setting of Z. Each register is allotted a time position in a cycle and is fed by a pulse such as ut1 in this time position. The c-wiper of the hundreds digit switch H applies starting potential to a busy chain circuit to energize the start relay of the next free link in the required hundreds group, e.g. A n10 in the link AS10-VLW10. The d-wiper of the hundreds switch H sends ut1 pulses over the n-wire and the switch VLW11 is caused to search for ut1, pulses applied over the d-wiper of the register connector switch and the d-bank of VLW10. When the contact having this pulse is found the coincidence circuit PS10 functions to operate relay P10 which stops the switch.. Contact 4p10 connects up a shunting resistance to reduce the voltage of the pulse ut1. Contact 3k10 disconnects the comparison circuit from the d-wiper of the hundreds digit switch. When the third digit is received by SE1 contact x is closed to short-circuit the resistance R1 thereby increasing the amplitude of the pulse applied over the d-wires to the link AS10- VLW10. On receipt of this increased amplitude pulse the switch AS10 is started by means not shown. The circuit PS10 is fed over the d-wiper of VLW10 with the pulse ut1. This pulse is also fed over the digit switches Z and one of the digit switches E1 ...EIO to the d-multiple of all the subscribers whose numbers have the wanted last two digits. When the selector AS10 encounters this pulse on its d-bank the coincidence circuit PS10 functions to operate P<SP>1</SP>10 to stop the switch and the through connection is thereupon established. Relay P<SP>1</SP>10 also earths the d-wire which thus causes the discontinuance of the application of one source of pulses ut1 to the comparison circuit PS thereby causing the release of the normally operated relay P to release the register. More detailed arrangements of the control circuits in the AS-VLW links are given, Fig. 13 (not shown). Thus separate coincidence circuits may be employed for controlling the switches AS, VLW each coincidence circuit firing a thyratron for controlling a stopping relay. A further thyratron is provided for responding to the increased amplitude pulses for starting the switch AS. If desired the switch VLW can also be started by increased amplitude pulses over the n-wires and the m-wires dispensed with. By suitable switching arrangements one coincidence' circuit and one starting thyratron mav be used for controlling both of the switches VLW and AS. In a modified form of register, Fig. 16, only one units digit switch E is required. A 10 x 10 array of thyratrons Rst are arranged to be energized over their anodes by the tens digit switch Z and over their grids by the units digits switch E so that only one is fired by the ut1.pulse in accordance with the settings of these switches. The resulting pulse is conveyed to the appropriate wire of the AS switch multiple via the cathode load of the fired thyratron. An arrangement, Fig. 17, is provided for testing the valves. A pulse position, not used for characterizing a register, is provided with a test pulse utp which is applied over switches c, d so as to fire a particular thyratron in accordance with the switch settings. The resulting pulse of anode current is detected via the transformer pTr and the coincidence circuit Rp to fire tube Rstp and operate relay R which controls the stepping of switches c and d. If R fails to operate an alarm may be given. Instead of permanently allocating a pulse position to a register, such a position may be allocated only temporarily when a connection is to be set up. The pulse position allocated to the register may be in accordance with the hundreds digit dialled and the testing circuits PS connected to a pulse source indicative of hundreds group served by the associated switch. Pulse coincidence testing may also be used for setting the switch AS1 when acting as a line finder, and also for its associated switch VLW1. To this end a special pulse position ut11 is allocated for indicating that a subscriber is calling, and a pulse in this position is fed by the calling subscriber's line relay to an appropriate contact in the bank of AS1. Simultaneously a relay common to the hundreds group seizes a register which hunts for a free outlet from VLW1 and applies the pulse ut11 to it. The register also applies the pulse ut11 to the stopping circuits of the AS1.- VLW1 link whereupon coincidence testing circuits therein are effective to stop AS1 on the calling subscriber's line and VLW1 on a free outlet. When the cut-off relay consequently operates it cuts off the pulse ut11. The register cuts off the pulse from the link and the VLW1 outlet and completes the connection using some other pulse in one of the manners mentioned above.